China
Africa
Explore chapters and articles related to this topic
Coastal water level variations
Published in Dominic Reeve, Andrew Chadwick, Christopher Fleming, Coastal Engineering, 2018
Dominic Reeve, Andrew Chadwick, Christopher Fleming
The Richter scale has several drawbacks. The first is that it is a comparative rather than absolute scale. The second is that it was developed for conditions specific to Southern California. An alternative measurement of earthquake magnitude, the Moment Magnitude scale (denoted by Mw), was designed to overcome the problems of the Richter scale. The Moment Magnitude is not comparative, has global applicability and gives magnitudes roughly equivalent to the Richter magnitudes. Both scales are still used, but the Moment Magnitude scale is gradually replacing the Richter scale and is preferred now by most seismologists. The numbers generated by the two scales are usually very similar (within 5%).
Environmental Health Emergencies, Disasters, and Terrorism
Published in Herman Koren, Best Practices for Environmental Health, 2017
The Richter scale, a common measurement scale for earthquakes, has certain limitations for very large earthquakes. It is a mathematical technique used to compare the size of earthquakes. The magnitude of the earthquake is reported in whole numbers and decimal fractions. It is based on a logarithmic scale and therefore an increase of 1 is actually 10 times greater rather than the initial number (e.g., a reading of 6 would be 10 times greater than a reading of 5). The Moment Magnitude Scale is more precise for large earthquakes because it is related to the total energy released during the earthquake. Intensity measures the amount of shaking at a given location, while moment measures the size of the earthquake at its source. (See endnote 9.)
Engineering Seismology Overview
Published in Hector Estrada, Luke S. Lee, Introduction to Earthquake Engineering, 2017
The strength of an earthquake can be more accurately measured using the moment magnitude scale, MW, which accurately measures a wide range of earthquake sizes and is applicable globally. This scale is a function of the total moment release by an earthquake. The moment is a measure of the total energy released. The concept of moment is adopted from mechanics and is defined as the product of the fault displacement and the force causing the displacement. A simple derivation of the moment, M0, is presented in Villaverde and is based on the size of the fault rupture, the slip amount, and the stiffness of the fractured rocks. That is, M0=GAfDs where: M0 is in dyne cm, which is a relatively small unit, 1 dyne cm = 1 × 10−7 N mG is the shear modulus of the rocks included in the fault in dyne/cm2, which ranges from 3.2 × 1011 dyne/cm2 in the crust to 7.5 × 1011 dyne/cm2 in the mantleAf is the area of the fault rupture in cm2Ds is the average fault slip or displacement in cm
Behavior factor prediction equations for reinforced concrete frames under critical mainshock-aftershock sequences using artificial neural networks
Published in Sustainable and Resilient Infrastructure, 2022
Elham Rajabi, Gholamreza Ghodrati Amiri
Chile earthquake (1960) as one of the most powerful earthquakes in the 20th century, consisted of foreshocks – one of magnitude 8.1 – mainshock with 9.4 – 9.6 moment magnitude scale and aftershock of Mw 7.2 that recorded 12 days later. Moreover, seismic sequence phenomenon consist of damaging aftershocks which even followed mainshock after long period, is observed in New Zealand earthquake (2010) so that an damaging aftershock with (M = 6.3) is occurred more than 4 months after than the main shock.